Leftist rebels ambushed an army patrol in southern Colombia Saturday and killed 14 soldiers from a unit that rushed to the area after being warned of a possible guerrilla takeover of a remote hamlet, the army said.

The ambush took place near the town of La Julia, 100 miles south of the capital, in what has long been the cradle of the Revolutionary Armed Forces of Colombia, or FARC, said Gen. Freddy Padilla, chairman of Colombia's Joint Chiefs of Staff.

``The attack lasted all day,'' Padilla told Caracol Radio late Saturday. ``We think it went badly for (the rebels) but we don't know for sure because operations are ongoing.''

Among the soldiers killed were two junior officers, Padilla said.

Acting on intelligence reports warning of a guerrilla assault on the village of La Julia, a mobile army unit from the U.S.-trained Omega Force was immediately deployed to the area, where they were surprised by the rebels, Padilla said.

The FARC has been trying to overthrow Colombia's government for almost a half-century. After being pursued the past four years by President Alvaro Uribe's military - the main recipient of $700 million in annual U.S. aid - its numbers are believed to have thinned to about 11,000 fighters.

But despite suffering important losses, the guerrillas are still capable of carrying out surprise attacks. To prove it, they have intensified their offensive since Uribe, Washington's staunchest ally in Latin America, was elected to a second four-year term in May.

As part of the show of force, they killed 17 police offices with makeshift mortars fired on a police station Nov. 1 in the town of Tierradentro, 230 miles northwest of Bogota.

The guerrillas were also blamed for a car bombing Oct. 19 at a military university in Bogota that injured 23 people and exploded a few feet from where Gen. Mario Montoya, head of the army, was giving a speech to foreign dignitaries.

On Thursday, Defense Minister Juan Manuel Santos said 575 members of the security forces had been killed so far in 2006 by guerrilla attacks, 10 percent fewer than in 2005.